Half of US flu vaccine supply suddenly not available

Oct 5, 2004 (CIDRAP News) – The vaccine supply for the soon-to-begin influenza season is suddenly in serious condition with news that Chiron Corp., maker of about half the US supply, has been ordered to stop production by British health authorities and will not be shipping its doses.

The reason for the 3-month cessation of Chiron's manufacturing license is unclear at this point. The company, based in Emeryville, Calif., and producing its Fluvirin vaccine in Liverpool, England, announced in late August that shipment of a small portion of its vaccine would be delayed because of contamination problems. Just last week, however, Chiron President and CEO Howard Pien reassured a Senate subcommitte that shipping would begin shortly and that his company's supplies would arrive in time for this season's vaccinations.

Then, early this morning US health officials were contacted with news that the Medicines and Healthcare Products Regulatory Agency (MHRA), the British counterpart of the US Food and Drug Administration, had suspended Chiron's license.

Chiron was to supply 46 to 48 million of the 100 million total doses of flu vaccine ordered for this year's vaccination program. Aventis Pasteur is to supply about 52 million doses of its Fluzone vaccine. MedImmune, maker of FluMist inhalable vaccine, will supply about 1.5 million doses. Although some Fluvirin has been received in the United States, none has been distributed.

In the 2003-2004 flu season, 87 million doses were made available. This supply proved to be inadequate when cases began occurring early and public demand soared—thus the 100 million planned doses this year.

A statement issued by the Department of Health and Human Services earlier today says that contingencies for the unexpected shortage are being pursued and that the immediate focus will be on getting vaccine to those most vulnerable. "We will need the help of the public, the public health community and the medical community to make sure that the vaccine goes to those who truly need it most," the release states.

In a press briefing this afternoon, Centers for Disease Control Director Julie Gerberding, MD, MPH, and National Center for Allergy and Infectious Disease Director Anthonly Fauci, MD, said that the Advisory Committee on Immunization Practices (ACIP) had been convened this morning to make recommendations on how the approximately 50 million doses of flu vaccine now expected should be distributed.

The ACIP recommendation is that the normally targeted groups for flu vaccination—those 65 years of age and over, pregnant women, and people 2 to 64 with certain chronic medical condition—should get it. In addition, healthcare workers and children aged 6 to 23 months, who have been newly targeted this year, should be vaccinated. Gerberding pointed out that the Chiron situation does not affect vaccinations for young children, as the pediatric vaccine is made by Aventis.

Healthy children over 23 months as well as healthy adults under 65 should defer getting vaccinations until such time as it can be determined that there is a surplus above that needed for the groups above, Gerberding said.

She further noted that public health officials have "taken steps today and before today" to deal with a shortage, stating that CDC had already been working on contingency plans in case there were further issues with the Chiron dosages or other unforeseen problems with the planned supply. She said CDC was "disappointed but not unprepared" and that everyone should "take a deep breath, this is not an emergency."

Fauci said that a new focus is being put on finding ways to make the flu vaccine supply more flexible and consistent. Currently, the virus used for influenza vaccines is grown in chicken eggs, so the process must start several months before vaccine is needed and the exact formulation is arrived at using virus strains that circulated in the past flu season. Fauci mentioned the process of reverse genetics for arriving at vaccine formulations and cell culture–derived vaccines as examples of important avenues of research that could imrpvoe upon vaccine reliability. He also said that preliminary findings suggesting that half-strength doses of flu vaccine might be protective in some groups are promising.

When asked whether the 50 million doses of vaccine now expected would be enough for the populations ACIP is targeting, Gerberding said that about 180 million people make up these groups but that "we never vaccinate all those." Patterns of actual vaccination from the past plus the fact that the Chiron vaccine doesn't affect the pediatric population's needs, she said, suggest that the now-limited supply may be sufficient.

Infectious disease expert Michael T. Osterholm, PhD, MPH, concurred with HHS and CDC recommendations, telling CIDRAP News that "In order to assure coverage of those at highest risk of serious complications [of flu], we're going to have to make sure the vaccine we do get is used very wisely."

Osterholm, director of the Center for Infectious Disease Research and Policy at the University of Minnesota, publisher of this Web site, said the occurrence of the Chiron situation, this year in particular as concern builds over a possible influenza pandemic arising from the avian flu outbreaks in Asia, "underscores critical gaps in our vaccine delivery infrastructure. . . . When this serious situation can arise in a 'routine' influenza season, just imagine if we suddenly have a pandemic influenza strain to deal with," he said

At today's press conference, Jesse Goodman, MD, MPH, director of the FDA's Center for Biologics Evaluation and Research, said that FDA experts are leaving tonight for England to confer with MHRA and review that agency's detailed report of what led to their decision on Chiron. They will also visit the manufacturing plant in Liverpool.